On openSUSE Leap 15.6 x86_64, with gcc 7 and test-case
gdb.base/condbreak-multi-context.exp I run into:
...
(gdb) print aaa^M
$3 = <optimized out>^M
(gdb) FAIL: $exp: start_before=true: scenario_1: print aaa
...
This is a regression since commit
86ac8c54623 ("Convert
lookup_symbol_in_objfile").
Likewise in test-cases gdb.cp/m-static.exp and gdb.cp/namespace.exp.
The failure is specific to using Dwarf v4:
- using target board unix/gdb:debug_flags=-gdwarf-5 fixes it
- using target board unix/gdb:debug_flags=-gdwarf-4 on Tumbleweed (with gcc 15
and Dwarf v5 default) triggers it
The variable we're trying to print, A::aaa is a static const int member:
...
class A : public Base
{
public:
static const int aaa = 10;
...
};
...
With Dwarf v5, we have this DIE:
...
<2><356>: Abbrev Number: 2 (DW_TAG_variable)
<357> DW_AT_name : aaa
<35c> DW_AT_linkage_name: _ZN1A3aaaE
<364> DW_AT_external : 1
<364> DW_AT_accessibility: 1 (public)
<364> DW_AT_declaration : 1
<364> DW_AT_const_value : 10
...
and the cooked index contains these corresponding entries:
...
[45] ((cooked_index_entry *) 0x7facf0004730)
name: _ZN1A3aaaE
canonical: _ZN1A3aaaE
qualified: _ZN1A3aaaE
DWARF tag: DW_TAG_variable
flags: 0x4 [IS_LINKAGE]
DIE offset: 0x356
parent: ((cooked_index_entry *) 0)
[52] ((cooked_index_entry *) 0x7facf0004700)
name: aaa
canonical: aaa
qualified: A::aaa
DWARF tag: DW_TAG_variable
flags: 0x0 []
DIE offset: 0x356
parent: ((cooked_index_entry *) 0x7facf00046d0) [A]
...
With Dwarf v4, we have instead the following DIE:
...
<2><350>: Abbrev Number: 3 (DW_TAG_member)
<351> DW_AT_name : aaa
<35b> DW_AT_external : 1
<35b> DW_AT_accessibility: 1 (public)
<35c> DW_AT_declaration : 1
<35c> DW_AT_const_value : 4 byte block: a 0 0 0
...
and there are no corresponding entries.
Fix this by adding an entry:
...
[47] ((cooked_index_entry *) 0x7f5a24004660)
name: aaa
canonical: aaa
qualified: A::aaa
DWARF tag: DW_TAG_member
flags: 0x0 []
DIE offset: 0x350
parent: ((cooked_index_entry *) 0x7f5a24004630) [A]
...
Add a regression test in the form of a dwarf assembly test-case printing the
value of variable A::aaa.
In the test-case, for A::aaa, DW_FORM_flag is used to encode
DW_AT_declaration. In v1 of this patch that mattered (because of using
has_hardcoded_declaration in abbrev_table::read), but that's no longer the
case. Nevertheless, also add an A::bbb using FORM_flag_present for
DW_AT_declaration (and while we're at it, DW_AT_external as well).
Also add two variants, for which <optimized out> is printed:
- A::ccc: a variant with DW_AT_location instead of DW_AT_const_value, and
- A::ddd: a variant without external.
This behavior is not part of the regression. I've reproduced it using a
system gdb based on 14.2. It's also not specific to using the cooked index,
it reproduces with -readnow as well.
Tested on x86_64-linux.
Approved-By: Tom Tromey <tom@tromey.com>
PR symtab/33415
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=33415
bool has_name = false;
bool has_linkage_name = false;
bool has_external = false;
+ bool has_const_value = false;
/* Now read in declarations. */
int num_attrs = 0;
if (is_csize && cur_attr.form == DW_FORM_ref4)
sibling_offset = size;
break;
+
+ case DW_AT_const_value:
+ has_const_value = true;
+ break;
}
switch (cur_attr.form)
the correct scope. */
cur_abbrev->interesting = true;
}
+ else if (cur_abbrev->tag == DW_TAG_member && has_const_value
+ && has_external)
+ {
+ /* For a static const member with initializer, gcc (and likewise
+ clang) generates a DW_TAG_member with a DW_AT_const_value
+ attribute when using DWARF v4 or earlier.
+
+ class A {
+ static const int aaa = 11;
+ };
+
+ <2><28>: Abbrev Number: 3 (DW_TAG_member)
+ <29> DW_AT_name : aaa
+ <34> DW_AT_external : 1
+ <34> DW_AT_declaration : 1
+ <34> DW_AT_const_value : 11
+
+ That's not the case if we move the initializer out of the class
+ declaration, we get a DW_TAG_variable representing the value:
+
+ class A {
+ static const int aaa;
+ };
+ const int A::aaa = 11;
+
+ <2><28>: Abbrev Number: 3 (DW_TAG_member)
+ <29> DW_AT_name : aaa
+ <34> DW_AT_external : 1
+ <34> DW_AT_declaration : 1
+ <1><41>: Abbrev Number: 6 (DW_TAG_variable)
+ <42> DW_AT_specification: <0x28>
+ <48> DW_AT_linkage_name: _ZN1A3aaaE
+ <4c> DW_AT_location : 9 byte block: (DW_OP_addr: 0)
+
+ We could try to cater here for the case that we have a
+ DW_AT_location instead of a DW_AT_const_value, but that doesn't
+ seem to be handled by the rest of GDB.
+
+ I did find an example of a non-external one for std::_Function_base
+ ::_Base_manager<get_compile_file_tempdir()::<lambda()> >
+ ::__stored_locally:
+
+ <4><27bd192>: Abbrev Number: 279 (DW_TAG_member)
+ <27bd194> DW_AT_name : __stored_locally
+ <27bd19e> DW_AT_accessibility: 2 (protected)
+ <27bd19f> DW_AT_declaration : 1
+ <27bd19f> DW_AT_const_value : 1 byte block: 1
+
+ but again that doesn't seem to be handled by the rest of GDB. */
+ cur_abbrev->interesting = true;
+ }
else if (has_hardcoded_declaration
&& (cur_abbrev->tag != DW_TAG_variable || !has_external))
{
that is ok. Similarly, we allow an external variable without a
location; those are resolved via minimal symbols. */
if (is_declaration && !for_specification
- && !(abbrev->tag == DW_TAG_variable && (*flags & IS_STATIC) == 0))
+ && !((abbrev->tag == DW_TAG_variable || abbrev->tag == DW_TAG_member)
+ && (*flags & IS_STATIC) == 0))
{
/* We always want to recurse into some types, but we may not
want to treat them as definitions. */
|| entry->tag == DW_TAG_entry_point)
kind = GDB_INDEX_SYMBOL_KIND_FUNCTION;
else if (entry->tag == DW_TAG_variable
+ || entry->tag == DW_TAG_member
|| entry->tag == DW_TAG_constant
|| entry->tag == DW_TAG_enumerator)
kind = GDB_INDEX_SYMBOL_KIND_VARIABLE;
switch (tag)
{
case DW_TAG_variable:
+ case DW_TAG_member:
case DW_TAG_enumerator:
case DW_TAG_constant:
flags = SEARCH_VAR_DOMAIN;
--- /dev/null
+# Copyright 2025 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+require dwarf2_support
+
+standard_testfile main.c .S
+
+set asm_file [standard_output_file ${srcfile2}]
+
+if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] } {
+ return
+}
+
+set int_size [get_sizeof "int" -1]
+
+Dwarf::assemble ${asm_file} {
+ cu {} {
+ DW_TAG_compile_unit {
+ DW_AT_language @DW_LANG_C_plus_plus
+ } {
+ declare_labels int_label
+
+ int_label: DW_TAG_base_type {
+ DW_AT_byte_size $::int_size DW_FORM_udata
+ DW_AT_encoding @DW_ATE_signed
+ DW_AT_name "int"
+ }
+
+ DW_TAG_class_type {
+ DW_AT_name "A"
+ } {
+ DW_TAG_member {
+ DW_AT_name "aaa"
+ DW_AT_type :$int_label
+ DW_AT_external 1 DW_FORM_flag
+ DW_AT_declaration 1 DW_FORM_flag
+ DW_AT_accessibility 1 DW_FORM_data1
+ DW_AT_const_value 10 DW_FORM_data1
+ }
+ DW_TAG_member {
+ DW_AT_name "bbb"
+ DW_AT_type :$int_label
+ DW_AT_external 1 DW_FORM_flag_present
+ DW_AT_declaration 1 DW_FORM_flag_present
+ DW_AT_accessibility 1 DW_FORM_data1
+ DW_AT_const_value 11 DW_FORM_data1
+ }
+ DW_TAG_member {
+ DW_AT_name "ccc"
+ DW_AT_type :$int_label
+ DW_AT_external 1 DW_FORM_flag
+ DW_AT_declaration 1 DW_FORM_flag
+ DW_AT_accessibility 1 DW_FORM_data1
+ DW_AT_location {
+ DW_OP_lit12
+ } SPECIAL_expr
+ }
+ DW_TAG_member {
+ DW_AT_name "ddd"
+ DW_AT_type :$int_label
+ DW_AT_declaration 1 DW_FORM_flag
+ DW_AT_accessibility 1 DW_FORM_data1
+ DW_AT_const_value 13 DW_FORM_data1
+ }
+ }
+
+ DW_TAG_subprogram {
+ MACRO_AT_func { "main" }
+ DW_AT_type :${int_label}
+ DW_AT_external 1 DW_FORM_flag
+ } {
+ }
+ }
+ }
+}
+
+if { [prepare_for_testing "failed to prepare" $testfile \
+ [list $asm_file $srcfile] {nodebug}] } {
+ return
+}
+
+# Regression test for PR symtab/33415. Print the value of A::aaa in:
+#
+# class A
+# {
+# public:
+# static const int aaa = 10;
+# };
+#
+# With DWARF 5, we get a DW_TAG_variable, but with DWARF 4, we get a
+# DW_TAG_member instead.
+gdb_test \
+ "print A::aaa" \
+ " = 10"
+
+# Variant with DW_FORM_flag_present instead of DW_FORM_flag.
+gdb_test \
+ "print A::bbb" \
+ " = 11"
+
+# Variant with DW_AT_location instead of DW_AT_const_value.
+gdb_test \
+ "print A::ccc" \
+ " = <optimized out>"
+
+# Variant without external.
+gdb_test \
+ "print A::ddd" \
+ " = <optimized out>"
projects / thirdparty / binutils-gdb.git / commitdiff
